Roller conveyer



A ril 13, 1937.

H. M. RISHEL ROLLER CONVEYER Filed March 23, 1936 I5 Sheets-Sheet lINVENTOR HUBERT M.H|5H|. 5y f Q 6?. QM

ATTORNEY5 April 13,1937. H. M. RISHE\L 2,077,188

ROLLER CONVEYEF Filed March 25, 1936 a Sheets-Sheet z INVENTOR HLJ BERTM-FHSHEL Patented Apr. 13, 1937 ROLLER CONVEYER Hubert M. Rishel,Edwardsville, Ill assignor to Mathews Conveyer Company, Ellwood City,Pa., a corporation of Pennsylvania Application March 23,

10 Claims.

This invention relates to new and useful improvements in conveyers, andmore particularly in roller conveyers.

In recent years, roller conveyers have become very popular in a greatmany industries as they offer a convenient and economical means oftransportation ofarticles and commodities from one place to another.Roller conveyers are commonly used as gravity conveyers and push lineconveyers. When used as gravity conveyers they are inclined or set onsufficient grade for the articles to move by gravity. When used as pushlines, the conveyers are set level or on a very slight grade. and theloads are usually pro- 15 pelled along the conveyers by hand. In rollerconveyers of this general type, as now commonly constructed, the rollersare usually mounted rigidly in stationary frames, generally known asframe rails. These frame rails, in turn, are sup- 20 ported bynon-yieldable supports such as steel frames, concrete piers, etc.

During recent yearsgmany new uses have been found for roller conveyers,particularly in large industrial plants such as foundries, and iron andsteel mills, where they are used for transporting heavy loads, castings,or groups of castings laid upon racksor skids, which in turn, arecarried upon roller conveyers. Roller conveyers are also now commonlyused in large sheet steel mills for 20 transporting heavy loads,consisting of packs of sheet metal, coils of strip steel, etc. Suchloads frequently weigh several tons. Conveyers having rigidly mountedrollers have proven satisfactory for handling relatively light loads,but such 35 conveyers have been found to be ineflicient in somerespects, when used for transporting extremely heavy loads, primarilybecause the major portion of the weight of the load may, at times, -betransmitted to but a single roller, or a few rollers, whereby suchrollers may become greatly overloaded. As an illustration, a load beingtransported over a conveyer and spanning or covering a given number ofrollers as, for example, ten, should contact each of the ten rollers 43spanned thereby, if the weight of theload is to be substantially equallydistributed on the ten rollers positioned therebeneath.

From actual experience, however, I have found that when a load istransported 'over a conveyer m in which the rollers are rigidly mounted,the entire weight of the load is not always uniformly distributed on allof the rollers spanned by the load. Such limited contact of the loadwith the rollers may result from various causes as, for example, aconveyer may have a high spot, caused by one or more of the rollersbeing disposed at a slightly higher elevation than adjacent rollers. Inthe construction of roller conveyers, it has been found most practicalto use antifriction 6U bearings of, the loose type. This, together with1936, Serial No. 70,202.

roller tube eccentricity and other slight inaccuracies inherent in theconstruction of roller conveyers, and variation in the diameter of therollers, as a result of wear, may result in the tops of the rollers of agiven conveyer, not all being disposed in the same plane. Such verticalmisalinement of the rollers of a conveyer may cause high spots in theupper surface of the conveyer. A similar condition may arise when a newunworn roller is interposed in an old conveyer, because the newrollermay be larger in diameter than the old or worn rollers of theconveyer. When the above condition is present, the major portion of theweight of the load will be momentarily transmitted to the high roller orrollers, as the load passes thereover, and when the mounting of therollers is such that the rollers cannot yield when subjected to anoverload, damage to the roller is likely to occur.

In other cases, the load itself may have an uneven or warped bottom,whereby the bottom of the load will not contact uniformly with all of.the rollers spanned thereby. When a load being transported over aconveyer in which the rollers are rigidly mounted, has a portiondepending below the bottom surface thereof, said depending portion maycause each roller engaged thereby to become temporarily overloaded,primarily because of the inability of the rollers to yield, whensubjected to an overload. Other irregularities in the conveying surfaceof the conveyer may also occur as a result of the supporting rails orfoundations of the rollers slightly settling or heaving, or because of ashock or jolt being imparted thereto when an article is carelesslyplaced on the conveyer. Variations may also result from expansion. orcontraction, due to temperature changes.

Obviously, when the entireweight of a load, weighing perhaps severaltons, is temporarily concentrated on a single roller or on a fewrollers, these rollers may become greatly overloaded,

which may permanently damage the roller bearings, or the rollersthemselves may become distorted or bent. I have also found that whenplacing a load on a conveyer, whose rollers are rigidly mounted, theimpact of the load with the rollers may cause the bearings to becomedamaged, or the rollers may become bent. Under these conditions, rollerand bearing replacements become necessary, and result in a highmaintenance and operating cost, and may often result in costly delays.

Another objection to the use of conveyers having non-resiliently mountedrollers, particularly when used for transporting relatively heavy loads,is that considerable power is usually required to propel the load overthe conveyer bed, because of the weight of the load not being uniformlydistributed on all of the rollers-disposed under the load. For example,when transporting a pack of metal sheets over a conveyer, the forwardlower corner of the pack may droop or sag, causing it to strike orimpinge against each roller, as the load is propelled along theconveyer. When the rollers are non-resiliently or rigidly mounted intheir supports, so that they cannot yield when subjected to an overload,the forward portion of the load must be relatively lifted each time itpasses over a roller, which tends to retard the forward movement of theload, and therefore requires that additional power be expended to propelthe load. If the conveyer is of the gravity type, the grade orinclination of the conveyer must be somewhat increased to allow for thiscontingency.

In the novel conveyer hereindisclosed, all of the above mentionedobjectionable features have been substantially eliminated. This, I haveaccomplished by resiliently mounting the rollers upon their supportingmeans in such a manner that when any roller, or number of rollers aresubjected to an overload, said overloaded rollers may yield to thepressure of the load, whereby their bearings are not likely to becomedamaged, nor the rollers bent or distorted. Means is also provided forcontrolling or regulating the precompression of the resilient meanssupporting the rollers, which pre-compression may be based upon themaximum weight of the load to be transported over the conveyer underordinary operating conditions and/or the carrying capacity of thebearings for the rollers. The resilient elements are preferably sotensioned that the rollers are normally retained at their uppermostpositions against suitable limit stops, when a load is being transportedover the conveyer, and the resilient elements yield or flex only whenthe rollers supported thereon are subjected. to an overload. By thusconstructing the conveyer, each roller will carry its approximateproportionate share of the weight of the load, whereby the size or loadcarrying capacity of the conveyer rollers required for each giveninstallation may readily be determined. To determine the loadcarryingcapacity of a givenconveyer, when the maximum weight of the load and theminimum number of rollers engaged by the load at one time,

- are 'known, the maximum weight of the load to be carried by theconveyer is divided by the minimum number of rollers engaged by the loadat one time, whereby the load per roller is readily determined.Heretofore, it has been diflicult to accurately determine the propersize rollers for a given conveyer installation because of the rollersbeing non-resiliently mounted in their supporting means, whereby theentire weight of the load may, at times, be concentrated on one or onlya few rollers.

Another advantage gained by resiliently mounting the rollers upon theirsupports, and pre-compressing the resilient elements, as hereindescribed, whereby each roller, when subjected to an overload, may yieldto the pressure of the load, is that less power is required to propelthe load. This results because, under normal operating conditions, noneof the rollers are unduly overloaded, by reason of their ability toyield when an overload is imparted thereto, thereby decreasing bearingfriction to a minimum. Also,

when the load is of such a nature that the front bottom edge or cornerthereof sags below the plane of the bottom of the load, and initiallyimpinges or strikes against each roller, as the load moves over theconveyer,,said rollers may yield forward movement of the load.

An important object of the present invention,

therefore, is to provide a roller conveyer wherein the rollers are soarranged relative to their sup-' porting means that each roller mayyield, when subjected to an overload, whereby bearing friction isreduced to a minimum, and damage to the bearings and rollers issubstantially eliminated. The novel construction of the conveyer alsoassures that the weight of the load being transported over the conveyerwill be substantially uniformly distributed on all of the rollersspanned by the load.

A further object is to provide a roller conveyer comprising a, pluralityof rollers having suitable resilient elements providing yieldablesupports therefor, whereby each roller may yield when engaged by anoverload, and means being provided for retaining said resilient elementsunder a predetermined compression, which may be easily determined by theload to be carried over the conveyer.

A further object is to provide a roller conveyer comprising a pluralityof independently movable, resiliently mounted rollers, so arranged thateach roller may yield independently of the others, when engaged by anoverload, whereby all of the rollers over which the load may besupported, will engage the load with a yieldable pressure, and wherebythe entire weight of the load will be substantially uniformlydistributed on all of the rollers engaged by the load.

' A further object is to provide a conveyer comprising a plurality ofindependently movable conveyer units, each comprising a. resilientlysupported frame in which suitable anti-friction rollers are mounted, andmeans being provided for supporting said frames in operative relation,whereby all of the rollers supported in said frames are spaced apartalong the conveyer.

A further object is to provide a roller conveyer comprising a pluralityof independently movable spring mounted rollers so constructed thatshocks, resulting from dropping loads on the conveyer, will be absorbedby the resilient mountings thereof, thereby substantially eliminatingdamage to the conveyer rollers and their bearings.

Other objects reside in the sectional construction of the conveyer, as awhole, which is composed of a plurality of spring mounted frames orunits, each carrying one or more rollers, and

, whereby each roller may yield when subjected to an overload; in theconstruction of the conveyer units each of which comprises spaced framemembers, between which anti-friction conveyer rollers are mounted, andeach frame member being supported upon a plurality of resilient elementshaving means for adjusting and retaining them under a predeterminedtension, and whereby, said elements may be precompressed in accordancewith the load to be carried so that, un-

dei' normal. operating conditions, said resilient elements will supporttheir respective rollers without yielding or flexing, but if one or moreof said rollers is, subjected to an overload, the resilient elementssupporting -said overloaded roller will yield, thereby to prevent theroller and its bearings from becoming damaged.

, Other objects of the invention will appear from the followingdescription and accompanying drawings and will be pointed out in theannexed claims.

In the accompanying drawings there has been disclosed a structuredesigned to carry out the various objects of the invention, but it is tobe understood that the invention is not confined to the exact featuresshown as various changes may be made within the scope of the claimswhich follow.

In the drawings:

Figure 1 is a perspective view showing a portion of a conveyerconstructed in accordance with the invention; I

Figure 2 is a detail cross-sectional view, showing the means providedfor resiliently supporting the rollers upon their supporting means;

Figure 3 is a detail plan view of a portion of Fi u Figure 4 is a detailsectional view showing a means for limiting upward movement of the sideframes, and which means also serves to retain adjacent frames inoperative relation;

Figure 5 is a plan view showing one of the units removed from itssupporting means;

Figure 6 is a side elevation of a portion of a conveyer, constructed inaccordance with the invention, and showing the rollers in their normalload-carrying positions;

Figure 7 is a diagrammatic view showing how each roller may yield, whenthe nature of the load is such as to impart an overload to'one or moreof the rollers;

Figure 8 is a diagrammatic view, showing a conveyer of the type hereindisclosed, in which one of the rollers is positioned above the adjacentrollers, as indicated by the dotted lines, which may result from any oneof several causes-already explained, whereby said relatively higherroller will be depressed by the load, as the latter travels over theconveyer, if the weight of the load, or a portion thereof, exceeds thenormal capacity of each roller;

Figure 9 diagrammatically illustrates how each roller of a conveyer ofthe type in which the rollers are rigidly mounted, may be greatly overloaded, because of the inability of the rollers to yield when subjectedto an overload;

Figure 10 is a diagrammatic view, illustrating the overload which may beimparted to certain rollers of a conveyer having non-yieldable rollers,when the rollers thereof are not horizontally alined;

Figure 11 is a plan view, showing a conveyer comprising two rows ofrollers, and illustrating the uniform distribution of the weight of theload on all of the rollers engaged thereby, when the rollers areresiliently mounted on their supports; and

Figure 12 is a plan view, showing a portion of a conventional type ofconveyer, wherein the rollers are rigidly mounted, and also illustratinghow the entire weight of the load may be carried by a very smallpercentage of the rollers over which the load is disposed.

The novel conveyer herein disclosed is best shown in Figure l, andcomprises a plurality of conveyer units, generally indicated by thenumeral 2. These units may be supported in iongitudinal alinement uponsuitable supporting members 4-4, which, in the present instance, areshown consisting of suitable beams or bars of angular cross-section,preferably arranged as shown in Figures 1 and 2.

The conveyer units 2 are preferably alike in construction and it willtherefore, be necessary to describe but one in detail. Each conveyerunit 2 comprises a frame consisting of side members 5-5 preferably tiedtogether by a crossmember l2 having its end portions suitably secured tothe horizontally flanged portions l3 of the side member 5, by such meansas welding. Each side member 5 is shown having an upstanding flange 6,which may be provided with suitable notches l in their upper edgesadapted to receive the ends of suitable axles 8, provided with suitablebearings (not shown) for rotatably supporting conveyer rollers 9. Theterminals of the axles are shown flattened on opposite sides. asindicated at H in Figure 2, to prevent relative rotation of the axles inthe side members 5 of the frame; If desired, the ends of the axles maybe squared, or otherwise shaped, to prevent relative rotation thereof,or the axles may be yieldably or resiliently support the conveyerrollers 99, the conveyer units 2 and 3 are shown supported upon aplurality of resilient elements such, for example, as springs I4. Thesesprings are interposed between the upper horizontal flanges l5 of thesupporting beams 4 and the horizontal portions l3 of the side framemembers 5 of the units.

To retain the springs M in their proper positions between the horizontalportions l3 and I5 of the frame members 5 and supporting beams 4,respectively, the parts l3 and I5 are shown provided with suitablebosses or centering elements I6 and I1, respectively, which arevertically alined and of such size as to be received within the illsprings, asbest shown in Figure 2, whereby the springs cannot becomedisarranged. The adjacent ends of the centering elements 16 and H arespaced apart, as shown at ill in Figure 2, to permit relative verticalmovement of the frame members 5, when a roller is engaged by anoverload.

The centering elements I6 and I! also function to providelimit stops forthe downward movement of the conveyer units, when subjected to anexcessive overload.

Another important feature of the invention resides in the provision ofmeans for maintaining the spring elements I4 under a predeterminedcompression, whereby the tensionunder which these springs areplaced, issuch as to prevent the rollers from yielding to any appreciable extent,when a load within the capacity of each individual roller passes overthe, conveyer, but which will permit each roller to yield, whensubjected to an overload. The pre-compression of the springs l4 may bedetermined for example by the weight of the load to be carried by theconveyer, and/or secured therein by suitable nuts 23. The studs is areinterposed between adjacent ends of the side members 5 of the frames ofadjacent units, as best illustrated in Figures 1 and 3, and theterminals of the frame members 5 may be notched, as shown at 24 (Fig.5), to receive the studs l9. Each stud has a head 25 adapted to beengaged by the upper faces of the terminals of adjacent frame members 5to limit the upward movement of the units. The springs It, beingnormally under compression, firmly hold the terminals of the .framemembers 5 in contact with the heads 25 of the studs, as will be clearlyunderstood by reference to Figure 1. The compression of the springs l4may be varied by relatively adjusting the studs I9 in the flanges 22 ofthe supporting beams 4, by

manipulation of the nuts 23, but is preferably 7 always such as toprevent the rollers from relatively yielding, when a uniformlydistributed load passes over the conveyer.

The ends of the conveyer may be composed of the relatively smallerconveyer units 3, each of which may comprise but a single conveyerroller 9, as clearly illustrated in Figure 1. Each end unit 3 comprisesside frames 26 having notched terminals 21 adapted to be engaged by theadjacent studs It, as clearly illustrated in Figure 1. The opposite endportions 28 of the frame members 26 of the unit 3 are shown apertured toreceive studs or bolts 29, adjustably secured to the flanges l5 of thesupporting beams 4, and having their heads 3| limiting upward movementof the unit 3. The unit 3 is supported upon springs I in a mannersimilar to the conveyer units 2. In some installations, the end unit 3,shownin Figure 1, may be dispensed with, in which case, the conveyer maybe composed of like units 2. This, however, is optional.

The novel conveyer, herein disclosed, has been found particularly usefulin large industries, such as foundries and steel mills, where extremely*eavy loads are conveyed from one place to another, although it may beused in many other ill places where it is essential that the weight ofthe load to be conveyed is distributed uniformly on all of the rollersspanned by the load at one time. The conveyer may comprise but a singlerow of rollers, as illustrated in Figure l, or, it may consist of two ormore rows of rollers, as illustrated in Figure 7, depending upon thesize and character of the load to be conveyed. The conveyer, as shown inFigures 1 and 6, is composed of a plurality of spring mounted unitsarranged in horizontal alinement lengthwise of the conveyer and retainedin such alinement by the studs l9.

In describing the operation of this novel conveyer, it is to beunderstood, as-previously stated, that one of the outstanding featuresof the invention resides in the pre-compression of the springs orresilient means which support the rollers, whereby the rollers do not,under ordinary operating conditions, yield to the weight of a uniformlydistributed load, but yield only when sub- Jected to an overload.

Figure 6 shows a load of normal weight traveling over a conveyer, inwhich the uppermost portions of all of the conveyers are shown retainedin the same horizontal plane by the action of the spring elements l4.When the tops of the rollers are thus alined, and the bottom of the loadis substantially smooth, and the weight of the load does not exceed thesafe carrying capacity of the rollers, the load will travel over theconveyer without depressing the rollers, as clearly illustrated inFigure 6. a

To afford aclear explanation of the invention, if a load to be conveyedweighs say, for example, 1200 pounds and each roller has a safe carryingcapacity of 300 pounds, then to avoid overloading the rollers, thespacing between the rollers should be such that at least four rollersare always engaged by the load. When thus spaced, the load imposed oneach roller will be within the safe carrying capacity of the rollers,individually, or about 300 pounds, assuming, of course, that the load issubstantially equally distributed on the four rollers.- Under the aboveconditions, the pre-compression of each pair of the spring elements I4is preferably at least 300 pounds, or 150 pounds per spring, whereby theelements will not yield when a uniformly distributed load passes overthe conveyer. Should the load, however, have an uneven bottom surface,as indicated at 33 in Figure 7, each time preventing the roller or itsbearings from becoming damaged. as a result of an overload beingtemporarily imposed thereon. In actual use it is impractical inproduction methods to accurately align the top surfaces of all of theresiliently mounted rollers so that they are in a single plane.

' While such adjustment might be made, the cost would be prohibitive andimpractical and unnecessary as a small fraction of an inch misalignmentof any one roller would be suflicient to throw an unequal distributionof the load on the rollers supporting the load were it not for theresilient mounting of the rollers. Furthermore in some instances, skidsare used to support the load over a plurality of rollers. These skidsare seldom if ever provided with true flat surfaces that are in a singleplane. One of the important features of the present invention is theautomatic distribution of the load on the rollers supporting the same assuch load passes thereover. In other words, the rollers that are high orslightly above other load supporting rollers, are depressed so that theload is distributed over all the rollers in contact therewith as itmoves over the conveyer. Hence accurate and true alignment of all of therollers is unnecessary and a roller alignment in accordance with modernproduction methods is entirely satisfactory. It is this automaticdistribution of the load which permits the load to move freely and withnoticeably less effort over a resiliently mounted roller conveyer asdistinguished from 'a rigidly mounted roller conveyer.

When the rollers are rigidly mounted, as shown in Figures 9 and 10, eachroller will be subjected to an overload, when engaged by the dependingportion 33 of the load, because the depending portion would cause theforward end of the load to lift, whereby the rollers positioned underthe intermediate portion of the load would likely not engage the load atall, resulting in the relatively few rollers temporarily engaged withthe load being severely overloaded. If the depending portion '33 of theload were located substantially at the center of the load, the entireweight of the load might momentarily be imposed on each roller, as theload travels over the conveyer, because of the inability of the rollersto yield when subjected to an overload. In a conveyer having rigidlymounted rollers, it is also difficult tov propel the load over theconveyer, particularly, if the bottom of the load is not reasonablysmooth.

In Figure 8, there is shown a conveyer in which the top of one of therollers, indicated by the numeral 34, is disposed at an elevationslightly above the tops of the rollers of theconveyer, as indicated bythe dotted lines. This may result from various causes as, for example, anew roller may be substituted for a damaged or worn one in a conveyer inwhich the rollers may have been reduced in diameter, as a result oflong, hard usage. In such a case, the uppermost portion of the newroller may project above the upper portions of the other rollers of theconveyer, resulting in a high spot in the surface of the conveyer.Variations in the horizontal alinement of the rollers may also resultfrom inaccuracies in manufacture. In conveyers of the type in which therollers are rigidly mounted, the entire weight of the load may bemomentarily imposed upon any or all rollers which are disposed at arelatively higher elevation than adjacent rollers, whereby such rollersmay become greatly overloaded, often resulting in bearing 'failure ordamage to the rollers themselves.

In a conveyer in which the rollers mounted upon resilient elements,which elements are preeompressed to support a load and preferablyprecompressed to a valueat least equal to the safe carrying capacity ofeach roller, a new roller interposed in the conveyer whose'uppermostportion may project above the upper portions of the adjacent rollers ofthe conveyer, will yield when an overload is imposed thereon, wherebythe load may pass smoothly over the high roller without shock or withoutgreatly overloading the new roller. When the rollers are rigidly mountedin their supports, any given roller thereof may be subjected to anoverload many times greater than that of its intended normal or safeload, and under certain conditions, half the weight of the load, orsometimes even the weight of the entire load may be momentarily imposedthereon, .depending upon the nature or character of the load, or thehorizontal alinement of the conveyer.

. This results because of the inability of each roller to yield, whensubjected to an overload.

To avoid frequent damage to the rollers ,of the conveyer in-which therollers are rigidly mounted, it is now common practice to make therollers relatively larger and heavier, than would otherwise be required,in order that the carrying ca pacity of each roller willbe ample tocarry the maximum overload which may be imposed thereon, when a load istransported over the conveyer.

In Figures 9 and 10, I have diagrammatically illustrated conveyers ofthe type in which the rollers are rigidly mounted. In Figure 9, it willbe noted that the load, because of the hump or depending portion 33, issupported only upon the rollers 35 and 36, whereby these two rollersmust carry the entire weight of the load or 600 pounds each, if theweight of the load is 1200 pounds. Such temporary overloading of therollers frequently results in damage to the rollers is in thepositionshown in Figure 10. When the load assumes the position indicated by thedotted because of the rollers being resiliently mounted,

whereby they may readily yield to abnormal pressures exerted thereon, aswhen temporarily overloaded. Under normal operating conditions, therollers 9'are retained in substantially horizontal alinement by thespring elements It and the studs IS, the latter providing means wherebythe uppermost portions of the rollers in a given conveyer may berelatively accurately alined, so that the weight of t a load having anormally smooth bottom will be uniformly distributed on all of therollers engaged by the load.

Also, because of the resilient mounting of the rollers and therelatively accurate alinement of the upper portions thereof, theconveyer may operate as a gravity conveyer, when disposed at a veryslight incline or grade, as compared to conveyers of the rigidly mountedroller type which, when used as gravity conveyers, for transportingheavy loads, must, of necessity, be disposed at a relatively greaterincline or grade in order that the load may travel thereoveruninterruptedly. A load may also be conveyed over the novel conveyer,herein disclosed, with very little effort, even though a portion of thebottom of the load may depend slightly below the bottom surface of theload, primarily, because as said depending portion engages each roller,each roller will yield againstthe tension of the springs l4, andindependently of adjacent rollers, to thereby permit the load to moveforwardly over the conveyor without any material resistance to thetraveling movement thereof. The conveyer herein disclosed, may also beused for transporting comparatively light loads, and loads which must betransported from one. place to another without shocks and jolts, itbeing understood that when the conveyer is designed for transportingrelatively lighter loads, the pre-compression of the springs [4 may becorrespondingly less, than when used for transporting relatively heavierloads.

In the drawings, I have shown the various conveyers as beingsubstantially straight. It is to be understood, however, that a conveyermade in accordance with the invention may be either straight or curved,or it may be inclined downwardly orupwardly, to meet the requirements ofeach installation. I have also found that by mounting the rollers uponpre-compressed resilient means, as herein disclosed, damage to theconveyer is not likely to occur when placing objects thereon, whether byhand or by an overhead orane, because of the fact that the resilientmountings of the rollers will absorb the load shocks imposed upon therollers of the conveyer,

when a heavy load'is roughly placed thereon.

In the appended claims, the term freely rotatable rollers is used in itsbroadest sense to mean that the rollers can rotate freely on theirsupports at all times irrespective of the weight of the load that ispassing thereover, and there are no brakes or other friction meansassociated therewith to limit free rotation of the rollers at any time.

The term uniformly distributed as used in the specification and claims,means a load supported on the rollers in such manner that each roller ofa group which is engaged by the load will bear a substantially equalshare of the load. Thus, if the load weighs 1200 pounds, and issupported on suitable skids which engage four rollers, then each rollerwill carry substantially 300 pounds. The term uniformly distributed" isused in the claims to define a particular ar- 10 rangement of the loadfor the conditions set forth in the claims and is not used to mean thatin actual practice all loads passing over the rollers must be uniformlydistributed thereon. V

A conveyer in which the rollers are resiliently mounted may be operatedcontinually for long periods without repair because of the ability ofeach roller to yield, when subjected to an overload, whereby theoperating and maintenance costs of the conveying system are greatlyreduced.

I claim as my invention:

1. In a conveyer for transporting loads, a plurality of resilient rollersupports, a plurality of freely rotatable rollers carried by saidsupports, and means for holding said resilient supports undercompression independently of the weight of the roller or load, saidmeans holding each of said supports under a substantial amount ofcompression and said rollers being arranged to rotate freelyirrespective of the weight of the load or the compression of theresilient supports. 2. In a conveyer designed for transporting loads ofor below. a predetermined maximum weight,

a pluralityof resilient roller supports, a plurality of freely rotatablerollers rotatably carried by said supports, and meansfor holding saidresilient supports under compression independently of the rollers orload, said means holding each of said resilient supports under acompression of such' value that uniformly. distributed relatively heavy40 loads of or below said maximum weight will pass over the conveyersubstantially smoothly and said rollers will be freely rotatable at alltimes irrespective of the amount of the compression of the resilientsupports.

3. In a roller conveyer designed for transporting loads of or below apredetermined maximum weight, a plurality of'resilient roller supports,a plurality of freely rotatable rollers carried by said supports andarranged to rotate freely irrespec- 50 tive of the weight of the load orthe deflection of said supports, and means for holding said resilientsupports under compression independently of the rollers or load, saidmeans holding each of the resilient supports under a compression of suchvalue that a uniformly distributed relatively heavy load of or belowsaid maximum weight will pass over the conveyer substantially smoothly.

4. In a roller conveyer designed for transporting loads of or below apredetermined maximum weight, a plurality of resilient roller supports,a roller carried byeach of said supports and arranged to rotate freelyirrespective of the weight of the load or the deflection of saidsupports, and means for compressing the resilient supports independentlyof the weight of the rollers or load, each of said resilient supportsbeing compressed by said means an amount substantially equal to. orgreater than the force applied by an average uniformly distributed heavyload below said maximum weight which is passing over the conveyer.

5. In a conveyer for transporting loads, a. plurality of resilientroller supp rts Dre-compressed .an appreciable amount, and a pluralityof freely rotatable rollers carried by said supports, the said rollersbeing arranged to rotate freely irrespective of the weight of the loador the compression of the resilient supports.

6. In a conveyer, a plurality of unit supports arranged end to end todefine a conveyer line, a plurality of rollers carried by each of saidunit supports, resilient means interposed between said unit supports andthe support for the conveyer, and means for holding said unit supportsand said resilient means under compression independently of the weightof the roller or load, said means holding each of said unit supportsunder a substantial amount of compression and said rollers beingarranged to rotate freely irrespective of the weight of the load or thecompression of the resilient supports.

'7. In a conveyer, a plurality of unit supports arranged end to end todefine a conveyer line, a plurality of rollers carried by each of saidunit supports, resilient means interposed between said unit supports andthe support for the conveyer, and means interposed between adjacent unitsupports and acting simultaneously thereon for holding said unitsupports and said resilient means under compression independently of theweight of the roller or load, said means holding each of said unitsupports under a substantial amount of compression and said rollersbeing arranged to rotate freely irrespective of the weight of the loador the compression of the resilient supports.

8. In a conveyer, a plurality of unit supports arranged end to .end todefine a conveyer, each of said unit supports comprising a frame havingspaced side members, rollers carried-by said side members, resilientmeans interposed between said side members and the support for theconveyer, and means for holding said unit supports and resilient meansunder compression independently of the weight of the roller or load,said means holding each of said unit supports under a substantial amountof compression and said rollers beingarranged to rotate freelyirrespective of the weight of the load or compression of the resilientsupports. 7

9. In a conveyer, a plurality of units each comprising spaced sidemembers, a support for said units, rollers mounted between the sidemembers of each unit, spring elements interposed in said side membersand the support to yieldably support the side members, and means forholding said spring elements and side members under compressionindependently of the weight of the rollers and load, said rollers beingarranged to rotate freely independent of the weight of the load or thecompression of the spring'elements and permitting independent verticalmovement of each unit when an overload is temporarily imposed thereon.

10. In a conveyer, 'a plurality of units each comprising spaced sidemembers, a support forsaid units, rollers carried by the side members ofsaid units, said units being arranged end to end on said support todefine a conveyer line, spring elements interposed between said sidemembers and the support to yieldably support the units, and means forpre-compressing said spring elements, said'rollers being freelyrotatable at all times independent of the weight of the load to betransported.

H'U'BERT M. RISHEL.

